islandzoom

So about a year ago last October, I found myself the owner of a 1999 NB Miata with a fairly extensive list of mods, not the least of which was a full Flying Miata FMII with all of the upgrades. It has FCM bilsteins, 500# front springs, 350# rear with 1 1/8" front bar and an 11mm rear. It made 278 RWHP on a local dyno, it drives great and puts down power fairly well( other than violent wheel hop on launch) with the help of an OS Giken rear diff. Wheels are 15x9 6UL with now 4 year old 225 Hoosier A7 front and rear.

I had previously been autocrossing my air cooled 1988 911 carerra, and enjoying it, until I had a ride in a well prepped NA with a turbo and ABS.....

My driving improved immensely during the first season in the Miata. I was regularly a runner up for FTD, and the car was alot of fun but PAX tells a different story and it seems like I should be alot quicker than I am if I really want to be competetive. I know there is still alot of room for improvement with my driving and I'm working on that, but I also know that the car is under prepped for SSM and I want to make a few tweaks and need some help deciding on whats next. As far as the current set up, the car stops great, turn in is crisp, and mid corner grip is excellent once the car takes a set. Corner exit the back end tends to wash out and I'm finding it hard to go faster due to the oversteer at the limit.

Tires are due for replacement, so I am thinking about also making the move to 11" 6UL's and 275 A7's, but I feel that I may be under sprung for the level of grip that would provide.

This is where I am at a crossroads. I do not want to re invent the wheel and start over and replace everything, so whats the best plan? Can the current set up handle the increased grip 11' wheels and 275's would provide? Should I make the move to a street tire like the rivals for the slightly more favourable index? Keep the 15x9's and just bump to 245's?

I'm hoping that with the help of the hive I can drill down and come up with a plan to make the car more capable as my driving improves and start to PAX better that I currently do.



Thanks for any feedback

bjorno

SSM is already past 200TW tires. Might as well go slicks.
CSP miatas now are running 10s, 11s, 12s, on NA horespower. SSM is a hard class for a miata, because its so open.
I'd say go for the fat hoosiers, up your spring rates to match, and add some aero (splitter, etc).

hector

I don't think you're going to get much feedback from the hive on this forum regarding autox. Most guys here are into tracking or making big power. Luckily you do have a couple of guys here who have built serious SSM autox cars and hopefully they'll chime in with what they think is priority to reducing the PAX gap.

But tell us the conditions you regularly autox in. Is it a smooth concrete surface? Is it a runway type course or is it full of sweepers? Does it usually rain? Are there ever national events there?

It would be good if you could also tell us how far off top PAX you are so you could maybe get better opinions on what we would do in your shoes. And how good those guys and their cars are. If you are out of top pax by less than 5% against guys who are decent and have decent cars for the class then you just need to drive better. Well honestly, needing to drive better is always priority number one but I'm sure you already knew that. What I'm trying to say is, how big of a fish do you have in your pond and how badly do you want to compete? In my area, no matter how well my car is set up, I am never going to be the guy to beat for top pax but I am usually within 5%. I might catch the top 5 sleeping on occasion, but that has to be a combination of me driving out of my mind and them having a bad day. Would having a better car help thrust me to the top, maybe a little. Would being at the same talent level as them help more, absolutely.

So in a sense, you have to be realistic with your goals. And remember that the PAX factor for SSM is not built around your car. It could get harder or softer. Also, top drivers tend to jump classes a lot and that alone could affect how big the gap can get.

Now if I were serious about competing for top pax and I had a SSM Miata like yours then there is no question what I would do. I would add more power, less weight, bigger tires, much better suspension, and big aero. Because to be honest with you, you don't have a SSM car unless you have all those things. But if I just wanted to keep trying to improve while having lots of fun I might go the 200tw direction in 245 if my area had some kind of STO (street touring over) class like they have in certain places.

And going with 275 A7's is a job. It's not just cut fenders and go. You will be playing with spacers and bump stops (if you use them) to make sure you keep the tires off the body or at least as much as you can. And no, 500lb springs won't cut it considering that STS cars are running 700lb springs or more in the front on 225 200tw tires. As it is you are likely riding the bump stops all the way in that car whenever in a turn with that set up you have. Consider a popular formula is 800/500 springs, 1.125 or 1.25 front bar and no rear bar. I'm not saying you can't be fast with what you have but no one I know who is fast is using what you have. And I am very much monkey-see, monkey-do.

If you haven't done so already, try searching for a few build threads on this forum. Search for Eric Anderson, Bob Bundy, navalhawkeye, Leafy. All these guys have built SSM cars and have had success at it so see what they have been up to.

I hope you get plenty more feedback. It's nice to have autox related discussions. You never know what you may learn.

islandzoom

Thank you Hector,

To answer your questions, the venue we have heres is small and bumpy with several different surfaces of old and new pavement mixed with some concrete in areas, there are also changing elevation and often off camber turns. I think a car sprung too stuffy may suffer a little and with the current set up I do not feel like I have ever felt the car bottom out.

The last event, and the first event of the year I was third overall for raw time, and 20th in pax out of 41 cars. It was a chilly 9 degrees which is far less than ideal for old Hoosiers. The shoulder season here are usually 10-15 degrees, which is one of the reasons I have considered trying a 200TW tire. In the summer months when its warm,t he grip from these tires old Hoosiers still amazes me. We do have an STSSM class, and the PAX is slightly more favourable.

Normally I am within a few 10th of FTD and10-14th place in PAX which would suggest that I should likely be a full 1.5-2 seconds quicker on an average course. I know for certain there is room to improve my driving, thats probably the biggest gain, but I also have a fairly consistent issue with the back end washing out and hitting a wall with my times. A lot of times I will go slower as the day goes on as I try and get faster...

For what I have seen, I know the car is under prepared by a long shot for SSM. The thing is I don't really want to start all over. I would like to increase tires size because I feel like no matter what I am under tired for SSM. I also would like to increase spring rates, but the FCM blisters are valved for the current rates and talking to FCM I would need to replace everything and not just coils. That being said, I wonder how much of a difference the valving is worth over just replacing springs and carrying on.

I'm currently considering removing the rear sway bar, moving up to 245's on the 9" wheels as the easy button for next season and just continue to work on my driving. That will still add more grip to marginal spring rates, so perhaps its down to just leave it alone, or go all the way?

ConeCrasher

iTrader: (1)

I think you need to decide if you are happy with FTD or a better pax result. If the later you need to change everything and start over. If FTD is good enough, buy new A7’s and as soon as the competition gets close buy new ones.

islandzoom

Sounds like you are correct based on the feedback so far. It is a slippery slope, but both options would give results. At this point, I would be happy to just maintain FTD, but the long term goal would be to be competitive on PAX as well so that I know I'm on par with the rest of the drivers, and the rest of the region. I'm thinking that I may be able to sell the current FCM and 6UL set up and get a chunk of the cost for the upgrades back.

That being said, if starting with a blank slate what would recommendations be for budget friendly coil overs?